From 959ecc48fc7506b9d7825ea70e40d92d9b308033 Mon Sep 17 00:00:00 2001 From: KAMEZAWA Hiroyuki Date: Wed, 15 Jun 2011 15:08:38 -0700 Subject: [PATCH] mm/memory_hotplug.c: fix building of node hotplug zonelist During memory hotplug we refresh zonelists when we online a page in a new zone. It means that the node's zonelist is not initialized until pages are onlined. So for example, "nid" passed by MEM_GOING_ONLINE notifier will point to NODE_DATA(nid) which has no zone fallback list. Moreover, if we hot-add cpu-only nodes, alloc_pages() will do no fallback. This patch makes a zonelist when a new pgdata is available. Note: in production, at fujitsu, memory should be onlined before cpu and our server didn't have any memory-less nodes and had no problems. But recent changes in MEM_GOING_ONLINE+page_cgroup will access not initialized zonelist of node. Anyway, there are memory-less node and we need some care. Signed-off-by: KAMEZAWA Hiroyuki Cc: Mel Gorman Cc: Dave Hansen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/memory_hotplug.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 9f646374e32f..02159c755136 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -494,6 +494,12 @@ static pg_data_t __ref *hotadd_new_pgdat(int nid, u64 start) /* init node's zones as empty zones, we don't have any present pages.*/ free_area_init_node(nid, zones_size, start_pfn, zholes_size); + /* + * The node we allocated has no zone fallback lists. For avoiding + * to access not-initialized zonelist, build here. + */ + build_all_zonelists(NULL); + return pgdat; } -- 2.30.2